Since 1990, only three Phillies relievers with at least 50 IP have finished a season with an ERA below 2.00. Billy Wagner did it in 2005 with a 1.51 ERA, Rheal Cormier did it in ’03 with a 1.70 ERA, and of course Brad Lidge did it in ’08 with a 1.95 ERA. Even if we go back to 1980, only Tug McGraw (1.46 in ’80) and Roger McDowell (1.11 in ’89) are added to the list.

Jose Contreras, the Phillies’ de facto closer in the wake of injuries to Brad Lidge and Ryan Madson, has a chance to compile the best season by a Phillies reliever in the last 30 years. Big Truck, as Charlie Manuel likes to call him, currently sits on an ERA lower than his WHIP, 0.63 to 0.70 and he has a strikeout-to-walk ratio of 20-to-2. If the season finished today, Contreras would have the highest strikeout rate and the lowest walk rate among the Phillies’ best relievers since 1980 as he is on pace for 81 strikeouts and 8 walks in 58 innings.

Since 1980, among relievers who have pitched at least 50 innings, a mere 73 have finished a season with a strikeout-to-walk ratio of 5.0 or higher. Contreras currently sits at 10.0, which would rank fourth-best in the last 30 years if the season ended today.

It is fair to say that Contreras is putting up Eckersleyan numbers out of the Phillies’ bullpen. The big question is, “Is it sustainable?”

Contreras was recently moved to the bullpen, so we do not have a good sample from which to draw conclusions. The Colorado Rockies converted Contreras from a starter to a reliever in late September last year after a right thigh strain. There, he threw seven and one-third innings in five appearances during the regular season and two innings in two appearances in the Division Series against the Phillies. However, during his days as a starter, Contreras never finished a season with a K/BB ratio higher than 2.4.

The strikeouts-per-nine rate of 12.6 seems unsustainable but Contreras has added a significant amount of velocity to each of his pitches as a reliever. His four-seamer last year averaged 92.0 MPH; this year, 94.5. His ’09 two-seamer: 77.6 MPH; this year, 81.3. And his slider last year: 84.8 MPH; this year, 88.5. In a sample of merely 14 innings, it is possible that these velocities will regress. Contreras may tire as the season grows longer. (However, warmer temperatures should also increase velocity by a small amount.)

His walk rate also seems fluky at 1.3 per nine innings. Since 1980, there have been 59 reliever-seasons with at least 50 IP and a K/9 rate of 12.0 or higher. Under the same criteria, there have been only 31 reliever-seasons with a BB/9 rate of 1.3 or lower. Throughout his starting career, Contreras displayed good but not great control with a career BB/9 of 3.3.

Contreras has induced swings at exactly the same rate as he did last year, 44.1%. However, this year he is inducing about 7% fewer swings at pitches in the strike zone and nearly 9% more swings at pitches outside the strike zone. It is no surprise that hitters are making contact 16% less than they did in ’09.

Right-handers haven’t done anything against Contreras this year as they are hitting for a .227 OPS against him (excluding yesterday’s appearance). Left-handers have a more respectable .715 OPS. In 2009, right-handers hit for a higher OPS than lefties. The difference could, of course, be attributed to a fluke within a very small sample. However, there is a noticeable change in his release point both against RH vs. LH and between 2009 and ’10.

RHH, 2009-10:

LHH, 2009-10:

(Those two fastballs all by themselves on the right on the 2009 chart are likely due to the Pitch F/X data entrant forgetting to append a negative sign.)

Contreras actually toyed with his release point against right-handed batters throughout 2009. A look at his release points by month:

It looks like Contreras settled on a three-quarters release point and it has been working out well for him thus far. It may even explain the tremendous success he has been enjoying in 2010. His success probably isn’t due to the medifast diet.

Overall, Contreras’ ERA is clearly lower than we should expect based on how he has pitched, but he has pitched extremely well as his 1.51 SIERA displays. As the Phillies entered 2010 with Brad Lidge and J.C. Romero on the disabled list and Ryan Madson soon joined them, the Jose Contreras free agent signing may prove to be the most important to the team this season. Given his strikeout stuff, he has been by far the Phillies’ best option to handle high leverage innings as his conversion of six of seven shutdown opportunities has shown.

When Ryan Madson‘s broken toe heals, should the Phillies return him to the set-up spot and continue to let Contreras close? As big a Madson supporter as I’ve been, even I have to say that Contreras is the better option for the final three outs (assuming, of course, that leveraging relievers instead of putting them in pre-defined roles is out of the question).